Deep space exploration satellite systems require high power, high gain antenna systems for transmitting data from the satellite back to a ground station located on the Earth. For example, the United States (US) National Aeronautics and Space Administration (NASA) is planning the development and launching of a Jupiter Icy Moons Orbiter (JIMO) to explore the nature and extent of habitable environments in the solar system. One of the main objectives of such a mission is to detect and analyze a wide variety of chemical species, including chemical elements, salts, minerals, organic and inorganic compounds, and possible biological compounds, in the surface of Jupiter's icy moons. The data collected needs to be transmitted over a dual band (e.g., Ka/X-band) at a high data rate.
Satellite systems are typically equipped with antenna systems including a configuration of antenna feeds that transmit and/or receive circularly polarized uplink and/or downlink signals. Typically, the antenna systems include one or more arrays of feedhorns, where each feedhorn array may include an antenna reflector for collecting and directing the signals. In order to reduce weight and conserve the satellite real estate, some satellite communications systems may use the same antenna system and array of feedhorns to receive the circularly polarized uplink signals and transmit the circularly polarized downlink signals. To effectuate more efficient transmissions, circularly polarized signals should be provided with substantially equal E-plane and H-plane radiation patterns and a reduced back-lobe. Otherwise, the signals propagating between a transmit antenna and a receive antenna may experience a loss of communication link power from becoming elliptically polarized through having a large axial ratio and from leaking radiated power through back-lobes. Table 1, below, demonstrates examples of the loss of communication link power (i.e., loss of gain) that can result from having large axial ratios. For example, as demonstrated in Table 1, if the space antenna has an axial ratio of 4 dB, the communication link to a perfect circularly polarized ground antenna loses 0.22 dB of gain. It is to be understood that the loss of communication link power demonstrated in Table 1 below is referring to one antenna (transmit or receive) having an axial ratio greater than 0 dB communicating with another antenna (transmit or receive) that has perfect circular polarization, thus having an axial ratio of 0 dB.
TABLE 1Axial Ratio (dB)Gain Loss (dB)10.011.50.0320.0630.1340.2250.33101.04151.72202.23
Many feedhorn antennas have been designed with features to specifically negate power loss caused by a back-lobe and a large axial ratio, such as by including iris pins or corrugated inner surfaces. However, during high-power transmissions, such designs often experience arcing through the accumulation of charge, thus breaking down. As such, these designs are often insufficient for high-power transmissions.